Ikki Tousen (一騎当千 Ikkitōsen?, lit. "a Mighty Knight who matches a Thousand Knights"), also known as Battle Vixens in North America, is a manga series written and illustrated by Yuji Shiozaki. Based on the classic Chinese novel Romance of the Three Kingdoms, the series revolves around an all-out turf war in the Kanto region of Japan where fighters known as Tōshi (闘士?, meaning "fighting soldier") from seven schools battle for supremacy. The story centers on Hakufu Sonsaku, a fighter who transfers to Nanyo Academy, one of the seven schools involved in the turf war.

The manga started serialization in the seinen manga magazine Comic Gum, and the first tankōbon was released in October 2000, with a total of 24 volumes available as of September 25, 2015. The manga was licensed in North America and the United Kingdom by Tokyopop with adaptation from Keith Giffen under the title Battle Vixens, and in Australia and New Zealand by Madman Entertainment.

A 13-episode anime adaptation produced by J.C.Staff aired between July and October 2003, on AT-X and other channels. A second anime season produced by Arms aired on AT-X between February and May 2007, spanning twelve episodes. A third anime season, also produced by Arms, aired on AT-X between June and August 2008, spanning twelve episodes and featuring an all-new plotline and characters. A fourth anime season produced by TNK and Arms aired on AT-X and other channels between March and June 2010, spanning 12 episodes and introducing new schools and characters. An anime OVA was announced by Media Factory, and premiered in Japanese theaters on November 12, 2011.

The first anime season was licensed in North America by Geneon Entertainment, but it is now licensed by Funimation after Geneon withdrew from the anime market. The second anime season is licensed in North America by Media Blasters. The third anime season was also licensed by Media Blasters,but it is now licensed by Funimation. The fourth anime season is also licensed by Funimation.